(i) Field to Which Invention Relates
The present invention is with respect to a switch for diverting spoiled items from an overlapped stream of folded paper products such as signatures and more specially coming from a folding machine and being forwarded to a delivery station, the folded signatures being supported on a transport system made up of a number of conveyor belt flights which are placed end to end and are made up of belts running round belt support rolls. At least the downstream roll of two belt rolls of a conveyor flight placed between two further conveyor flights is able to be moved bodily as a switch roll by way of a driving part under the control of a control unit, so that the distance from the switch roll from the next conveyor flight is changed.
(ii) The Prior Art
In a known system on these lines the space between one conveyor belt flight and the next one may be changed for forming a switch system or diversion by making the downstream conveyor belt flights shorter or longer. To do this, the downstream belt support roll of this upstream conveyor belt flight is moved backwards and forwards while keeping at the same level. For taking care of the change in length, that is to say without stretching the belts, the belts have their lower runs guided over a take-up roll which may be moved bodily and which is moved backwards and forwards in the opposite direction to the bodily moved belt support roll. The change in overall length of the conveyor belt flight to make it longer or shorter and for this reason the change in position of the belt support roll and of the guide or take-up roll has to take place very quickly for neatly separating a part of the stream of overlapped signatures, which is in order, from a further part, in which the signatures are spoiled. For this reason high inertia forces come into play so that the system may only be worked with sharp jerks and there is a high wear rate. At the same time, the driving system has to be designed with a large size and a high power so that the switch system is made higher in price and more complex. A further point is that the loop of belt needed on changing the length of the belt and run round the take-up roll takes up much space, quite in addition to the more complex mechanical design of the machine necessary for the take-up roll and the direction changing rolls near it at the ends of the conveyor flight. Furthermore, because the belts are changed in direction so many times, their working life is made shorter.
In the case of a further known system (see German Auslegeschrift specification No. 2,229,414) for forming a switch there is a plunging spade placed over the overlapped stream of signatures so that is may be moved for pushing its spade edge between one signature and the next one so as to have the effect of forwarding the signatures running onto it to a downstream belt system. In the case of this system as well, the plunging spade has to be sharply moved and speeded up and the downstream belt system for taking up the separated or diverted signatures has to be suddenly speeded up to make certain of neatly diverting the overlapped stream, so that high inertia forces come into play and the system is generally moved in sharp jerks causing a high wear rate. It is furthermore likely for the plunging spade to be run up against a folded signature so that the signatures coming thereafter have to be moved thereover and a pile-up is likely. Even in addition to this, the system for driving and movingly supporting the plunging spade and the belt system used therewith is very complex from the engineering point of view.
In the case of a further known system (see German Auslegeschrift specification No. 2,848,010) a conveyor belt flight has a generally thick downstream belt support roll which is used with a further short conveyor belt flight placed thereover and supported on a rocking frame, said short flight being able to be moved, for forming a switch, about its upstream belt roll (which is placed resting against the thick front belt roll) into a higher-up and further-back position, said belt roll being able to be drivingly joined up with a separating roll, which may be moved into a position between one folded signature and the next one. In the normal transport position of the signatures the said thick downstream belt roll and the short belt flight used therewith are placed on the two sides of an S-like transport way with the purpose of causing a certain fanning of the folded signature forced through this S-like way of opening. A shortcoming is however that because of the change in direction of the overlapped stream along a letter S, a heavy force is produced acting on the signatures and may be the cause of undesired creasing and the like of thick signatures when there is a small overlapping distance. Furthermore the printing ink, which is still soft, on the work may be smeared. For this reason this known system is not able to be used for high press speeds.